I want to tension my wire rope. What fittings can I choose?
This information is designed for decorative suspension and architectural wires - NOT for lifting applications
There are endless applications which require a tension wire, such as cable railing, trellis, suspension cable for display, or catenary wires. A catenary wire is a taut suspension and support cable for electrical cables, lights, decorations etc. TECNI stocks a wide variety of fittings which will enable you to create a cable assembly which suits your needs, using the most appropriate depending on the application.
Turnbuckles used to be the standard method to tension cables and may still be used. However, we find most of our customers want something more attractive for their cable wire rope railings, suspension or catenary wire.
Simple Catenary System or Tension Wire with Turnbuckle
Turnbuckles provide good tension, want the industrial look or a cheap and cheerful solution. They come in a wide range of sizes and styles for your tension wire and can be closed body, open body, stainless steel and galvanized with hook, eye and jaw ends. Turnbuckles are also known as open and closed body rigging screws, tensioners, straining screws, barrel strainers or adjusters.
Turnbuckle used below for a simple tension wire/catenary system. Ideal for suspending power cables or lights and decorations at home and garden.
Create a thimble eye on each end of your cable, either with ferrules or wire rope grips, and attach a turnbuckle to one end. Tension achieved by turning the turnbuckle.
Self Assembly Tensioning Terminals
Our self-assembly threaded tensioners are all made of 316 stainless so ideal for tension wires in and outside. They are attractive and very easy to install, versatile and can be used for numerous tensioning applications. Available with a left and right hand thread means they can be tensioned on the fittings or on the outside. They can be used with different standard M6 and M8 fittings like studding, dual threaded screws and threaded jaws for fixing.
TECNI DIY Female Threaded Terminal
Our best selling product is this tensioner which is UK manufactured and ideal for cable railing, balustrading, trellis and display, shelf, light and curtain hanging for example. These terminals are available with left and right hand thread in M6 for 3 and 4mm cable and M8 for 5 and 6 mm cable.
To achieve tension going into the post as here you need a left and right hand fitting at opposite ends.
If you are going through a post or eyebolt and tightening up on the outside then you need two right hand fittings.
M6 Right Hand Tension Fitting
Designed for use with 2.5 and 3mm cable, this M6 TECNI Tension Fitting is only available in right hand only so has to be tensioned on the outside. Used in conjunction, for example, with the Standard SE70 Trellis Eye fitting it is ideal for horizontal and vertical tension wires.
TECNI TENSOR Fitting
Like the DIY Female Threaded fitting above, and available for use with 4-6mm cables, the Tensor fitting illustrated here is perfect for architectural and suspension applications, cable railing and balustrading where strength is key. It has an inbuilt tensioner, and like the DIY fitting it is easy to fit onsite. The strength difference comes from the fact that the Tensor fitting is swageless whereas the cable in the DIY fitting is held with grub screws.
Swage studs are permanently fixed tensioning fittings that provide high strength and are aesthetically pleasing. The termination is about 90% of the cable’s breaking load. The disadvantage is that a hydraulic press is needed to swage studs over 4mm so we generally manufacture the cable for customers. TECNI does sell a hydraulic hand crimping tool to allow you to press up to 4mm studs on site.
Can you get to the outside of the end fixing?
If you can access the thread on each end of the assembly once it has gone through the end post, joist or fitting that it is fixed to then you can use Swage Studs on their own. A hex nut is used to tension the wire. You may have to hacksaw remove the excess screw and dress up the end as best you can, usually done with a dome nut.
Here you don’t see the swage end of the stud as it is inside the joist.
If you can’t access the outside of the fixing, then swage studs can be incorporated into a closed turnbuckle body/rigging screw with an eye or jaw on the other end to provide tension.
Swage stud with rigging screw and threaded jaw attached to an eyebolt.
Swage stud into the stairs.
Swageless studs can be a very good alternative to swage studs as they allow you to make up the assemblies on site. They are equally as strong as swage terminals and can be fitted to rigging screws to the same effect as swage studs.
Kwik Loc Grips and TECNI Grip fittings are good for hand tensioning because they are micro-adjustable, however you cannot achieve full bow string like tension with them.
The cables can be as tight as possible, as much as 1,000 kgs if you can get that. It all depends on the strength of your design and often on your installers as to how accurate they can be and how tight they can pull the cable.
With tension cables the end fixings are always the weakest point. For example when a cable is tensioned with one of our DIY terminals, the tension in the cable is approx 80kgs. If you then want 9 runs as on cable railing for example, multiple the 80kgs by 9 and the amount of tension increases significantly, thus requiring end fixings or posts that will sustain 720 kgs of pull.
TECNI specializes in stainless steel wire rope and wire cable but we can provide galvanized, PVC and nylon coated and can even coat it in a colour of your choice.
If you do not need to put a loop in the end of the cable to attach the tensioner to, ie if you are using a swage stud or DIY tensioner then most customers prefer to use 1x19 construction because it likes to go in straight runs as it is the least flexible of the cables. It is also the strongest and smoothest. A stair landing bend of up to 35 degrees is achievable with 1x19. If the angle is greater choose a 7x7 or even the most flexible 7x19 construction cable. Right angles are not feasible.